Question: $ {-5\cdot \left[ \begin{array}{cc} 1 & 2 \\ 0 & 4 \\ -1 & -1 \end{array} \right]=}$
Solution: The Strategy To multiply a matrix by a scalar, we multiply each term of the matrix by the scalar. Multiplying each term $ {\begin{aligned}-5\cdot \left[\begin{array}{rr} {1} & {2} \\ {0} & {4} \\ {-1} & {-1} \end{array}\right]&=\left[\begin{array}{rr} -5\cdot{1} & -5\cdot{2} \\ -5\cdot{0} & -5\cdot{4} \\ -5\cdot{-1} & -5\cdot{-1} \end{array}\right] \\\\&=\left[\begin{array}{rr} {-5} & {-10} \\ {0} & {-20} \\ {5} & {5} \end{array}\right]\end{aligned}}$ Summary $ {-5\cdot \left[ \begin{array}{cc} 1 & 2 \\ 0 & 4 \\ -1 & -1 \end{array} \right]=\left[ \begin{array}{cc} -5 & -10 \\ 0 & -20 \\ 5 & 5 \end{array} \right]}$